Orange Wheat Blossom Midge Kit
Since the first major outbreak in 1993, wheat blossom midge (Sitodiplosis mosselana) has occurred as a serious problem in parts of the UK every year. This culminated in 2004, when damage caused by the pest increased to higher levels than ever before. Spraying was frequently done too late and losses in 2004 are estimated at £60 million.
The orange-coloured larvae feed on wheat, barley and rye grain. Each larva reduces grain size by 30-50%. Pericarp damage allows easier water entry, often resulting in sprouting in the ear. Damaged seeds are also susceptible to attack by pathogenic fungi.
Although chemical control measures are available, their efficacy is highly dependent on precise timing of spray applications. Until now, checking crops each evening during the ear emergence period has been the only way to determine which crops were at risk.
The integrated control of wheat blossom midge LINK project has identified the optimum pheromone release rate for use in pheromone traps in the UK. Pheromone traps catch male midges during their mating flight.
The Wheat Blossom Midge Monitoring Kit
The monitoring kit consists of two Easiset Delta Traps, two pheromone lures, two plastic sticky inserts, a spatula for removing dead midges and a trapping record card. The pheromone lure attracts the male midges to the trap as soon as they emerge.
The traps should be positioned a week before the first ears emerge. This should be at GS45, when the boots are swollen. Traps should then be left in position until the latest crop in the vicinity reaches flowering (GS61).
Traps should be attached to stakes at crop height.
Regardless of field size, a minimum of two traps should be used in each field being monitored. Two traps should be placed in each area of the farm with different microclimates or growing a different variety.
Traps placed in sheltered moist valleys may catch higher numbers than more exposed sites.
The lures have a field life of at least six weeks and do not need to be changed during the monitoring season.
Trapped insects and debris should be removed from the trap at each visit.
Traps should be regularly monitored and catches recorded every 2-3 days.
Spray Thresholds
It is only possible to provide a provisional threshold recommendation at the moment. Research is continuing under the Integrated Control of Wheat Blossom Midge (LINK Programme) to refine these further. During the 2004 season, many growers responded to late to achieve adequate control. Once a spray decision has been made, timely intervention is essential.
Pheromone Trap Threshold: 20 - 30 midges over two nights Action: Inspect any susceptible crops in mid-ear emergence(GS51) for midge infestation. Treatment is recommended where ear infestation threshold is exceeded. Midge activity after the start of flowering may be ignored. Eggs laid after GS61 do not develop properly due to the increasing toxicity of the developing grain.
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